British Standard BS 7671 is the national standard in the United Kingdom for low voltage electrical installations.

The IET (Institution of Engineering and Technology) has published wiring regulations in the United Kingdom since 1882. Since their 15th edition (1981), these regulations have closely followed the corresponding international standard IEC 60364.

Today, they are largely based on the European Committee for Electrotechnical Standardization (CENELEC) harmonization documents, and therefore are technically very similar to the current wiring regulations of other European countries.

It is also used as a national standard by Mauritius, St Lucia, Saint Vincent and the Grenadines, Sierra Leone, Sri Lanka, Trinidad and Tobago, and Uganda, and several other countries who base their wiring regulations on BS 7671.

In 1992, the IEE Wiring Regulations became British Standard BS 7671 and they are now treated similar to other British Standards. They are maintained by the Joint IET/BSI Technical Committee JPEL/64, the UK National Committee for Wiring Regulations. Although the IET and BSI are non-governmental organizations and the Wiring Regulations are non-statutory, they are referenced in several UK statutory instruments.

The BSI publish numerous titles concerning acceptable standards of design/safety/quality etc. in various fields. BS 7671 : 2001 (AMD No 2 : 2004) concerns the safety of electrical wiring in buildings (dwellings, commercial, industrial or otherwise) – generally known as the “Regs” (wiring regulations) – and succeeds the previous publication the 16th Edition of the Wiring Regulations.

The 17th edition, released in January 2008, is the latest edition of BS7671, and became effective for all installations designed after 1 July 2008.

One of the more significant changes is (chapter 41) that 30mA RCD’s will be required for socket outlets that are for use by ordinary persons and are intended for general use.

This improves the level of protection against electrical shock in the UK to a level comparable to that in other EU countries. The 17th edition incorporates new sections relating to microgeneration and solar photovoltaic systems.

The Institution of Electrical Engineers (I.E.E.) was a British professional organisation of electronics, electrical, manufacturing, and Information Technology professionals, especially electrical engineers. The I.E.E. was founded in 1871 as the Society of Telegraph Engineers, changed its name in 1880 to the Society of Telegraph Engineers and Electricians and changed it again to the Institution of Electrical Engineers in 1889. It was Incorporated by a Royal Charter in 1921.

In 2006, the I.E.E. merged with the Institution of Incorporated Engineers (I.I.E.) to form the Institution of Engineering and Technology (I.E.T.). Before the merger, the I.E.E. was the largest professional engineering society in Europe, with a worldwide membership of around 120,000.

The IEC is the international organisation for the preparation of safety standards and other standards in the area of electrical engineering. International orientation on the focus of its activities is a stated objective of electrotechnical standardisation.

Considerably more than 50 % of the production of the German electrotechnical industry is exported – international standardisation is, therefore, a basis for economic success.

The International Electrotechnical Commission and its national counterparts (IET, IEEE, VDE, etc.) define high voltage circuits as those with more than 1000 V for alternating current and at least 1500 V for direct current, and distinguish it from low voltage (50 to 1000 V AC or 120 to 1500 V DC) and extra-low voltage ( below 50 V AC or below 120 V DC) circuits. This is in the context of building wiring and the safety of electrical apparatus.

Low Voltage

This is an electrical engineering term that broadly identifies safety considerations of an electricity supply system based on the voltage used. While different definitions exist for the exact voltage range covered by “low voltage”, most usually 50 to 1000 V AC, the most commonly used ones include “mains voltage”, 230 V AC.

“Low voltage” is characterised by carrying a substantial risk of electric shock, but only a minor risk of electric arcs through air. “Low voltage” is distinguished from:

Extra low voltage – which carries a much reduced risk of electric shock
High voltage – where electrical arcing is a substantial additional risk

The IEE published Amendments No2 to BS 7671:2001 (the IEE Wiring Regulations) on 31st March 2004. The amendment specifies new cable core colours for all new fixed wiring in electrical installations in the UK. These new electrical wiring colours are sometimes referred to as ‘harmonised’ colours, as they will bring the UK more closely in line with practice in mainland Europe.

Electrical installations work commencing before 31st March 2006 may use the new harmonised cable colours or the pre-existing colours, but not both. Work commencing on site after 31st March 2006 will be required to comply with the harmonised cable core colours and must not use the old colours.

Full details of the changes can be found in Amendment No 2 (AMD 14905) to BS7671:2001 – which is shown above. They are also within the new version of BS7671:2001 (incorporating Amendments 1 & 2) which was published on the 31st March 2004.

K&L Electrical’s electricians are qualified to the new 17th Edition IEE Wiring Regulations and City & Guilds 2391 Inspection & Testing. (Certification of Electrical Installations).

All electrical work meets the requirements of Part P electrical safety.

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